Adjustable pitch-board



Patented June 16, 1885.

flttorney.

Inventor Joseph M Prior by Fig.5.

(No Model.)

J. M. PRIOR.

ADJUSTABLE PITCH BOARD.

Witnesses I Unrrnn STATES Parent @rrren.

JOSEPH M. PRIOR, OF BOSTON, MASSACHUSETTS.

ADJUSTABLE PITCH-=BOARD.

SPECIFICATION forming part of Letters Patent No. 320,090, dated June 16, 1885.

Application filed April 7, 1885.

To all wiwm it may concern:

Be it known that I, JosnrH M. PRIOR, a citizen of the United States, residing at East Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Adjustable Pitch- Boards, of which the following, taken in connection with the accompanying drawings, is a specification.

My invention relates to adjustable pitchboards in which two arms are fixed at right angles to each other,and combined with a third or hypotenuse arm, thus forming a rightangled triangle, the sides of the same being adjustable to adapt the board for use in measuring the height of rise, width of tread, and angle of pitch of any flight of stairs.

The object of my invention is to produce an adjustable pitch-board which shall be simpler in construction and more readily adjusted than those heretofore in use, and at the same time shall present a true and unbroken edge close to the work, to insure accuracy in marking; and it consists oftwo fixed arms forming a right-angled eornerpiece, each of said arms being grooved upon its outer edge and provided with an extension-piece fitted to slide within said groove, the thickness of said extension-pieces at their outer edges being equal, or nearly so, to thethickness of the fixed arms in the grooves of which they slide, and to which they are fitted by a beveled or mitered joint at the corners thereof, said extensionpieces being held in position by suitable screws, as will be further described.

It also consists in the arrangement of a hypotenuse arm adj ustably secured to the outer ends of the extension-arms above mentioned, by means of screws passing through slots in said hypotenuse arm, and engaging with swivel-nuts fixed in the ends of the sliding extension-arms, all of which will be best understood by reference to the following description of the drawings, in which Figure 1 is an elevation of apitch-board embodying my invention; Fig. 2, a central section of the same. Fig. 3 is an elarged section of the same. Fig. 3 is an enlarged sec tion on line :0 a: on Fig. 1. Fig. 4. is an e11- larged section 011 line y y on Fig. l, and Figs. 5 and 6 are respectively an elevation and an end view of the hypotenuse arm.

(No model.)

The pitch-board here described is designed to be made of metal, and is composed of the two arms A A, and secured in one piece or secured immovably together at right angles to each other, the sliding extensioupieees B B, and the hypotenuse arm D. Each of the arms A A has formed in its outer edge a groove, a, to which grooves are fitted so as to slide therein the extension-pieces B B, the edges or corners of the arms A A upon either side of the said grooves being beveled so as to make the grooves flaring at their outer edges, while the pieces B B are made of a corresponding shape, thus forming a beveled or mitered joint at the corners b I), all as shown in Fig. 3.

The width of the outer edges 01' faces of the pieces B B is thus made equal to the thickness of the arms A A, so that the working or marking edge of the pitch-board will always be of even thickness whether the pieces B B be extended or closed, and a true edge will accordingly be presented close to the work. The pieces B B are secured in position by means of the thumb-screws E E, passing through slots 0 c in the inner edges of the arms A A, and screwing into said pieces B B.

In the enlarged outer end of each of the ex tension-pieces B B is formed a V-shaped re cess, d, in which the nut F is pivoted by means of the pin 6, which passes through said nut and the end of the piece B.

G G are two thumb-screws, which, passing through slots f f in the ends of the hypotenuse arm D, are screwed into the swivel-nuts F F, and serve to secure the arm D in its proper position. The screws G G are each provided with two shoulders, g g, between which the arm D may slide when being adjusted, the slots f f extending to the ends of said arm, so that it may readily be engaged with or removed from said screws.

The arm D may be made light and strengthened by means of the ribs h it along its outer side. It should be of a length equal to the distance between the outer ends of the pieces B B when they are drawn out to their full extent, and is made of a width somewhat greater than the thickness of the arms A A, so that the pitch-board may be used on the edge of a board or plank in the same manner as a common T or try square, the arm D forming the head or guide.

To facilitate the accurate adjustment of the pitch-board, graduated scales are out upon the sides of the extension-pieces B B, as shown at z 2'.

Before adjusting the pieces B B the screws G G, which hold the arm D, should be loosened, to allow said arm to slide thereon, the swivelnuts F F allowing said screws to adapt themselves to the varying inclination of the arm D, and when the pieces B B have been secured in their proper positions the screws G G are again tightened, and the board is ready for use.

In marking out the stringers for a flight of stairs it iscommon practice to use a straightedge upon the workas a guide for the pitch-- board. In this case the arm D and screws G G are removed, and the ends of the .pieces B B are placed against the straightedge or guide, when the board may he slid along in the usual way. If, however, it is preferred to true up the edge of the plank or work to be cut, and use said edge as a guide for the pitchboard in marking out the stairs, the arm D should be secured in its proper position, and the pitch-board may then be used after the manner of a trysquare, as before described. The board being exactly alike on its two sides, is readily reversible for use on rightor left; hand work.

The method of fitting the sliding extension arms within the grooves a a, whereby the fullwidth of the marking-edge-is retained throughi out its length, is an important improvement; upon adjustable pitch-boards heretofore made, inasmuch as the marking is often done with a! knife or other sharp instrument, and any variations in the thickness of the edge would bei troublesome. The beveled 0r mitered joint before mentioned allows the screws E E togf draw the pieces B B more tightly into their respective grooves, and thus prevents them from slipping. The exact shape of the inner portion of said grooves, as seen in cross-section,

Fig. 3, is not material, as they may be square,

as shown, or V-shaped, or semicircular, provided that at their outer edges they be so shaped as to form the beveled joint before described. v

The location of the screws E E, projecting .from the inner edges of the arms A A, allows extension-arms B B, extra holes may be tapped therein, and adapted to receive the screws E E, as shown at It It, Fig. 2. "j

The shoulders gon the screws G G may be made by turning down said screws to a smaller diameter between said shoulders and the shoulders 9, instead of forming the shoulders g by means of collars or enlargements upon said screws, as shown in the drawings.

What I claim as my invention, and desire to secure by Letters Patent of the United States, is-

1. In an adjustable pitch-board, the combination of two fixed arms secured together at right angles to each other, each arm having in its outer edge a-groove, the edges of which are beveled or flared outwardly in such manner that the width of said groove across the said outer edges thereof shall be substantially equal to the thickness of said fixed arm, two extension-pieces fitted to slide within said grooves, and having a width of marking-face substantially equal to the thickness of said fixed arms, and means of securing said extension-pieces in any desired position within said grooves, as and for the purposes described.

2. In an adjustable pitch-board, the combination of two fixed arms secured together at right angles to each other, each provided with a groove in its outer and a slot in its inner edge, twoextension-pieces fitted to and adapted to slide within said grooves, andtwo or more screws passing through the slots in the inner edges of said fixed arms, and adapted to secure said extension-pieces in any desired position within said grooves, substantially as and for the purposes described.

3. The combination of the fixed arms A A, having grooves a a, extension-pieces B B, means of securing said extension-pieces in any desired position within the grooves a a, the hypotenuse arm D, screws G G, and swivelnutsF F, substantially. as and for the purposes described. I

4.. In an adjustable pitch-board, a hypotenuse arm made thicker than the remaining portion of the board, so as to form a projecting lip or edge upon either side of said board, substantially as and for the purposes described.

In testimony whereof Ihave-signed my name to this specification, in the presence of two subscribing witnesses, on this 3d day of April, A. D. 1885.

JOSEPH M. PRIOR. 

